// Formatting library for C++ - experimental format string compilation
//
// Copyright (c) 2012 - present, Victor Zverovich and fmt contributors
// All rights reserved.
//
// For the license information refer to format.h.

#ifndef FMT_COMPILE_H_
#define FMT_COMPILE_H_

#include "format.h"

FMT_BEGIN_NAMESPACE
namespace detail
{

// An output iterator that counts the number of objects written to it and
// discards them.
class counting_iterator
{
   private:
    size_t count_;

   public:
    using iterator_category = std::output_iterator_tag;
    using difference_type = std::ptrdiff_t;
    using pointer = void;
    using reference = void;
    using _Unchecked_type = counting_iterator;  // Mark iterator as checked.

    struct value_type
    {
        template <typename T>
        void operator=(const T &)
        {
        }
    };

    counting_iterator() : count_(0) {}

    size_t count() const { return count_; }

    counting_iterator &operator++()
    {
        ++count_;
        return *this;
    }
    counting_iterator operator++(int)
    {
        auto it = *this;
        ++*this;
        return it;
    }

    friend counting_iterator operator+(counting_iterator it, difference_type n)
    {
        it.count_ += static_cast<size_t>(n);
        return it;
    }

    value_type operator*() const { return {}; }
};

template <typename Char, typename InputIt>
inline counting_iterator copy_str(InputIt begin, InputIt end, counting_iterator it)
{
    return it + (end - begin);
}

template <typename OutputIt>
class truncating_iterator_base
{
   protected:
    OutputIt out_;
    size_t limit_;
    size_t count_ = 0;

    truncating_iterator_base() : out_(), limit_(0) {}

    truncating_iterator_base(OutputIt out, size_t limit) : out_(out), limit_(limit) {}

   public:
    using iterator_category = std::output_iterator_tag;
    using value_type = typename std::iterator_traits<OutputIt>::value_type;
    using difference_type = std::ptrdiff_t;
    using pointer = void;
    using reference = void;
    using _Unchecked_type = truncating_iterator_base;  // Mark iterator as checked.

    OutputIt base() const { return out_; }
    size_t count() const { return count_; }
};

// An output iterator that truncates the output and counts the number of objects
// written to it.
template <typename OutputIt,
          typename Enable =
              typename std::is_void<typename std::iterator_traits<OutputIt>::value_type>::type>
class truncating_iterator;

template <typename OutputIt>
class truncating_iterator<OutputIt, std::false_type> : public truncating_iterator_base<OutputIt>
{
    mutable typename truncating_iterator_base<OutputIt>::value_type blackhole_;

   public:
    using value_type = typename truncating_iterator_base<OutputIt>::value_type;

    truncating_iterator() = default;

    truncating_iterator(OutputIt out, size_t limit) : truncating_iterator_base<OutputIt>(out, limit)
    {
    }

    truncating_iterator &operator++()
    {
        if (this->count_++ < this->limit_) ++this->out_;
        return *this;
    }

    truncating_iterator operator++(int)
    {
        auto it = *this;
        ++*this;
        return it;
    }

    value_type &operator*() const { return this->count_ < this->limit_ ? *this->out_ : blackhole_; }
};

template <typename OutputIt>
class truncating_iterator<OutputIt, std::true_type> : public truncating_iterator_base<OutputIt>
{
   public:
    truncating_iterator() = default;

    truncating_iterator(OutputIt out, size_t limit) : truncating_iterator_base<OutputIt>(out, limit)
    {
    }

    template <typename T>
    truncating_iterator &operator=(T val)
    {
        if (this->count_++ < this->limit_) *this->out_++ = val;
        return *this;
    }

    truncating_iterator &operator++() { return *this; }
    truncating_iterator &operator++(int) { return *this; }
    truncating_iterator &operator*() { return *this; }
};

// A compile-time string which is compiled into fast formatting code.
class compiled_string
{
};

template <typename S>
struct is_compiled_string : std::is_base_of<compiled_string, S>
{
};

/**
  \rst
  Converts a string literal *s* into a format string that will be parsed at
  compile time and converted into efficient formatting code. Requires C++17
  ``constexpr if`` compiler support.

  **Example**::

    // Converts 42 into std::string using the most efficient method and no
    // runtime format string processing.
    std::string s = fmt::format(FMT_COMPILE("{}"), 42);
  \endrst
 */
#ifdef __cpp_if_constexpr
#define FMT_COMPILE(s) FMT_STRING_IMPL(s, fmt::detail::compiled_string, explicit)
#else
#define FMT_COMPILE(s) FMT_STRING(s)
#endif

#if FMT_USE_NONTYPE_TEMPLATE_PARAMETERS
template <typename Char, size_t N, fmt::detail_exported::fixed_string<Char, N> Str>
struct udl_compiled_string : compiled_string
{
    using char_type = Char;
    constexpr operator basic_string_view<char_type>() const { return {Str.data, N - 1}; }
};
#endif

template <typename T, typename... Tail>
const T &first(const T &value, const Tail &...)
{
    return value;
}

#ifdef __cpp_if_constexpr
template <typename... Args>
struct type_list
{
};

// Returns a reference to the argument at index N from [first, rest...].
template <int N, typename T, typename... Args>
constexpr const auto &get([[maybe_unused]] const T &first, [[maybe_unused]] const Args &...rest)
{
    static_assert(N < 1 + sizeof...(Args), "index is out of bounds");
    if constexpr (N == 0)
        return first;
    else
        return get<N - 1>(rest...);
}

template <typename Char, typename... Args>
constexpr int get_arg_index_by_name(basic_string_view<Char> name, type_list<Args...>)
{
    return get_arg_index_by_name<Args...>(name);
}

template <int N, typename>
struct get_type_impl;

template <int N, typename... Args>
struct get_type_impl<N, type_list<Args...>>
{
    using type = remove_cvref_t<decltype(get<N>(std::declval<Args>()...))>;
};

template <int N, typename T>
using get_type = typename get_type_impl<N, T>::type;

template <typename T>
struct is_compiled_format : std::false_type
{
};

template <typename Char>
struct text
{
    basic_string_view<Char> data;
    using char_type = Char;

    template <typename OutputIt, typename... Args>
    constexpr OutputIt format(OutputIt out, const Args &...) const
    {
        return write<Char>(out, data);
    }
};

template <typename Char>
struct is_compiled_format<text<Char>> : std::true_type
{
};

template <typename Char>
constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos, size_t size)
{
    return {{&s[pos], size}};
}

template <typename Char>
struct code_unit
{
    Char value;
    using char_type = Char;

    template <typename OutputIt, typename... Args>
    constexpr OutputIt format(OutputIt out, const Args &...) const
    {
        return write<Char>(out, value);
    }
};

// This ensures that the argument type is convertible to `const T&`.
template <typename T, int N, typename... Args>
constexpr const T &get_arg_checked(const Args &...args)
{
    const auto &arg = get<N>(args...);
    if constexpr (detail::is_named_arg<remove_cvref_t<decltype(arg)>>())
    {
        return arg.value;
    }
    else
    {
        return arg;
    }
}

template <typename Char>
struct is_compiled_format<code_unit<Char>> : std::true_type
{
};

// A replacement field that refers to argument N.
template <typename Char, typename T, int N>
struct field
{
    using char_type = Char;

    template <typename OutputIt, typename... Args>
    constexpr OutputIt format(OutputIt out, const Args &...args) const
    {
        return write<Char>(out, get_arg_checked<T, N>(args...));
    }
};

template <typename Char, typename T, int N>
struct is_compiled_format<field<Char, T, N>> : std::true_type
{
};

// A replacement field that refers to argument with name.
template <typename Char>
struct runtime_named_field
{
    using char_type = Char;
    basic_string_view<Char> name;

    template <typename OutputIt, typename T>
    constexpr static bool try_format_argument(
        OutputIt &out,
        // [[maybe_unused]] due to unused-but-set-parameter warning in GCC 7,8,9
        [[maybe_unused]] basic_string_view<Char> arg_name, const T &arg)
    {
        if constexpr (is_named_arg<typename std::remove_cv<T>::type>::value)
        {
            if (arg_name == arg.name)
            {
                out = write<Char>(out, arg.value);
                return true;
            }
        }
        return false;
    }

    template <typename OutputIt, typename... Args>
    constexpr OutputIt format(OutputIt out, const Args &...args) const
    {
        bool found = (try_format_argument(out, name, args) || ...);
        if (!found)
        {
            throw format_error("argument with specified name is not found");
        }
        return out;
    }
};

template <typename Char>
struct is_compiled_format<runtime_named_field<Char>> : std::true_type
{
};

// A replacement field that refers to argument N and has format specifiers.
template <typename Char, typename T, int N>
struct spec_field
{
    using char_type = Char;
    formatter<T, Char> fmt;

    template <typename OutputIt, typename... Args>
    constexpr FMT_INLINE OutputIt format(OutputIt out, const Args &...args) const
    {
        const auto &vargs = fmt::make_format_args<basic_format_context<OutputIt, Char>>(args...);
        basic_format_context<OutputIt, Char> ctx(out, vargs);
        return fmt.format(get_arg_checked<T, N>(args...), ctx);
    }
};

template <typename Char, typename T, int N>
struct is_compiled_format<spec_field<Char, T, N>> : std::true_type
{
};

template <typename L, typename R>
struct concat
{
    L lhs;
    R rhs;
    using char_type = typename L::char_type;

    template <typename OutputIt, typename... Args>
    constexpr OutputIt format(OutputIt out, const Args &...args) const
    {
        out = lhs.format(out, args...);
        return rhs.format(out, args...);
    }
};

template <typename L, typename R>
struct is_compiled_format<concat<L, R>> : std::true_type
{
};

template <typename L, typename R>
constexpr concat<L, R> make_concat(L lhs, R rhs)
{
    return {lhs, rhs};
}

struct unknown_format
{
};

template <typename Char>
constexpr size_t parse_text(basic_string_view<Char> str, size_t pos)
{
    for (size_t size = str.size(); pos != size; ++pos)
    {
        if (str[pos] == '{' || str[pos] == '}') break;
    }
    return pos;
}

template <typename Args, size_t POS, int ID, typename S>
constexpr auto compile_format_string(S format_str);

template <typename Args, size_t POS, int ID, typename T, typename S>
constexpr auto parse_tail(T head, S format_str)
{
    if constexpr (POS != basic_string_view<typename S::char_type>(format_str).size())
    {
        constexpr auto tail = compile_format_string<Args, POS, ID>(format_str);
        if constexpr (std::is_same<remove_cvref_t<decltype(tail)>, unknown_format>())
            return tail;
        else
            return make_concat(head, tail);
    }
    else
    {
        return head;
    }
}

template <typename T, typename Char>
struct parse_specs_result
{
    formatter<T, Char> fmt;
    size_t end;
    int next_arg_id;
};

constexpr int manual_indexing_id = -1;

template <typename T, typename Char>
constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str, size_t pos,
                                                  int next_arg_id)
{
    str.remove_prefix(pos);
    auto ctx = basic_format_parse_context<Char>(str, {}, next_arg_id);
    auto f = formatter<T, Char>();
    auto end = f.parse(ctx);
    return {f, pos + fmt::detail::to_unsigned(end - str.data()) + 1,
            next_arg_id == 0 ? manual_indexing_id : ctx.next_arg_id()};
}

template <typename Char>
struct arg_id_handler
{
    arg_ref<Char> arg_id;

    constexpr int operator()()
    {
        FMT_ASSERT(false, "handler cannot be used with automatic indexing");
        return 0;
    }
    constexpr int operator()(int id)
    {
        arg_id = arg_ref<Char>(id);
        return 0;
    }
    constexpr int operator()(basic_string_view<Char> id)
    {
        arg_id = arg_ref<Char>(id);
        return 0;
    }

    constexpr void on_error(const char *message) { throw format_error(message); }
};

template <typename Char>
struct parse_arg_id_result
{
    arg_ref<Char> arg_id;
    const Char *arg_id_end;
};

template <int ID, typename Char>
constexpr auto parse_arg_id(const Char *begin, const Char *end)
{
    auto handler = arg_id_handler<Char>{arg_ref<Char>{}};
    auto arg_id_end = parse_arg_id(begin, end, handler);
    return parse_arg_id_result<Char>{handler.arg_id, arg_id_end};
}

template <typename T, typename Enable = void>
struct field_type
{
    using type = remove_cvref_t<T>;
};

template <typename T>
struct field_type<T, enable_if_t<detail::is_named_arg<T>::value>>
{
    using type = remove_cvref_t<decltype(T::value)>;
};

template <typename T, typename Args, size_t END_POS, int ARG_INDEX, int NEXT_ID, typename S>
constexpr auto parse_replacement_field_then_tail(S format_str)
{
    using char_type = typename S::char_type;
    constexpr auto str = basic_string_view<char_type>(format_str);
    constexpr char_type c = END_POS != str.size() ? str[END_POS] : char_type();
    if constexpr (c == '}')
    {
        return parse_tail<Args, END_POS + 1, NEXT_ID>(
            field<char_type, typename field_type<T>::type, ARG_INDEX>(), format_str);
    }
    else if constexpr (c == ':')
    {
        constexpr auto result = parse_specs<typename field_type<T>::type>(
            str, END_POS + 1, NEXT_ID == manual_indexing_id ? 0 : NEXT_ID);
        return parse_tail<Args, result.end, result.next_arg_id>(
            spec_field<char_type, typename field_type<T>::type, ARG_INDEX>{result.fmt}, format_str);
    }
}

// Compiles a non-empty format string and returns the compiled representation
// or unknown_format() on unrecognized input.
template <typename Args, size_t POS, int ID, typename S>
constexpr auto compile_format_string(S format_str)
{
    using char_type = typename S::char_type;
    constexpr auto str = basic_string_view<char_type>(format_str);
    if constexpr (str[POS] == '{')
    {
        if constexpr (POS + 1 == str.size()) throw format_error("unmatched '{' in format string");
        if constexpr (str[POS + 1] == '{')
        {
            return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
        }
        else if constexpr (str[POS + 1] == '}' || str[POS + 1] == ':')
        {
            static_assert(ID != manual_indexing_id,
                          "cannot switch from manual to automatic argument indexing");
            constexpr auto next_id = ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
            return parse_replacement_field_then_tail<get_type<ID, Args>, Args, POS + 1, ID,
                                                     next_id>(format_str);
        }
        else
        {
            constexpr auto arg_id_result =
                parse_arg_id<ID>(str.data() + POS + 1, str.data() + str.size());
            constexpr auto arg_id_end_pos = arg_id_result.arg_id_end - str.data();
            constexpr char_type c =
                arg_id_end_pos != str.size() ? str[arg_id_end_pos] : char_type();
            static_assert(c == '}' || c == ':', "missing '}' in format string");
            if constexpr (arg_id_result.arg_id.kind == arg_id_kind::index)
            {
                static_assert(ID == manual_indexing_id || ID == 0,
                              "cannot switch from automatic to manual argument indexing");
                constexpr auto arg_index = arg_id_result.arg_id.val.index;
                return parse_replacement_field_then_tail<
                    get_type<arg_index, Args>, Args, arg_id_end_pos, arg_index, manual_indexing_id>(
                    format_str);
            }
            else if constexpr (arg_id_result.arg_id.kind == arg_id_kind::name)
            {
                constexpr auto arg_index =
                    get_arg_index_by_name(arg_id_result.arg_id.val.name, Args{});
                if constexpr (arg_index != invalid_arg_index)
                {
                    constexpr auto next_id = ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
                    return parse_replacement_field_then_tail<
                        decltype(get_type<arg_index, Args>::value), Args, arg_id_end_pos, arg_index,
                        next_id>(format_str);
                }
                else
                {
                    if constexpr (c == '}')
                    {
                        return parse_tail<Args, arg_id_end_pos + 1, ID>(
                            runtime_named_field<char_type>{arg_id_result.arg_id.val.name},
                            format_str);
                    }
                    else if constexpr (c == ':')
                    {
                        return unknown_format();  // no type info for specs parsing
                    }
                }
            }
        }
    }
    else if constexpr (str[POS] == '}')
    {
        if constexpr (POS + 1 == str.size()) throw format_error("unmatched '}' in format string");
        return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
    }
    else
    {
        constexpr auto end = parse_text(str, POS + 1);
        if constexpr (end - POS > 1)
        {
            return parse_tail<Args, end, ID>(make_text(str, POS, end - POS), format_str);
        }
        else
        {
            return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]}, format_str);
        }
    }
}

template <typename... Args, typename S, FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
constexpr auto compile(S format_str)
{
    constexpr auto str = basic_string_view<typename S::char_type>(format_str);
    if constexpr (str.size() == 0)
    {
        return detail::make_text(str, 0, 0);
    }
    else
    {
        constexpr auto result =
            detail::compile_format_string<detail::type_list<Args...>, 0, 0>(format_str);
        return result;
    }
}
#endif  // __cpp_if_constexpr
}  // namespace detail

FMT_MODULE_EXPORT_BEGIN

#ifdef __cpp_if_constexpr

template <typename CompiledFormat, typename... Args,
          typename Char = typename CompiledFormat::char_type,
          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
FMT_INLINE std::basic_string<Char> format(const CompiledFormat &cf, const Args &...args)
{
    auto s = std::basic_string<Char>();
    cf.format(std::back_inserter(s), args...);
    return s;
}

template <typename OutputIt, typename CompiledFormat, typename... Args,
          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
constexpr FMT_INLINE OutputIt format_to(OutputIt out, const CompiledFormat &cf, const Args &...args)
{
    return cf.format(out, args...);
}

template <typename S, typename... Args, FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
FMT_INLINE std::basic_string<typename S::char_type> format(const S &, Args &&...args)
{
    if constexpr (std::is_same<typename S::char_type, char>::value)
    {
        constexpr auto str = basic_string_view<typename S::char_type>(S());
        if constexpr (str.size() == 2 && str[0] == '{' && str[1] == '}')
        {
            const auto &first = detail::first(args...);
            if constexpr (detail::is_named_arg<remove_cvref_t<decltype(first)>>::value)
            {
                return fmt::to_string(first.value);
            }
            else
            {
                return fmt::to_string(first);
            }
        }
    }
    constexpr auto compiled = detail::compile<Args...>(S());
    if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>, detail::unknown_format>())
    {
        return format(static_cast<basic_string_view<typename S::char_type>>(S()),
                      std::forward<Args>(args)...);
    }
    else
    {
        return format(compiled, std::forward<Args>(args)...);
    }
}

template <typename OutputIt, typename S, typename... Args,
          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S &, Args &&...args)
{
    constexpr auto compiled = detail::compile<Args...>(S());
    if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>, detail::unknown_format>())
    {
        return format_to(out, static_cast<basic_string_view<typename S::char_type>>(S()),
                         std::forward<Args>(args)...);
    }
    else
    {
        return format_to(out, compiled, std::forward<Args>(args)...);
    }
}
#endif

template <typename OutputIt, typename S, typename... Args,
          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n, const S &format_str,
                                         Args &&...args)
{
    auto it = format_to(detail::truncating_iterator<OutputIt>(out, n), format_str,
                        std::forward<Args>(args)...);
    return {it.base(), it.count()};
}

template <typename S, typename... Args, FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
size_t formatted_size(const S &format_str, const Args &...args)
{
    return format_to(detail::counting_iterator(), format_str, args...).count();
}

template <typename S, typename... Args, FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
void print(std::FILE *f, const S &format_str, const Args &...args)
{
    memory_buffer buffer;
    format_to(std::back_inserter(buffer), format_str, args...);
    detail::print(f, {buffer.data(), buffer.size()});
}

template <typename S, typename... Args, FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
void print(const S &format_str, const Args &...args)
{
    print(stdout, format_str, args...);
}

#if FMT_USE_NONTYPE_TEMPLATE_PARAMETERS
inline namespace literals
{
template <detail_exported::fixed_string Str>
constexpr detail::udl_compiled_string<remove_cvref_t<decltype(Str.data[0])>,
                                      sizeof(Str.data) / sizeof(decltype(Str.data[0])), Str>
operator""_cf()
{
    return {};
}
}  // namespace literals
#endif

FMT_MODULE_EXPORT_END
FMT_END_NAMESPACE

#endif  // FMT_COMPILE_H_
